The present invention generally relates to inkjet printers and in particular to a system and method for optimizing ink drying time through the incorporation of a system of multiple spaced printheads.
Inkjet printers are commonplace in the computer field. These printers are described by W. J. Lloyd and H. T. Taub in xe2x80x9cInk Jet Devices,xe2x80x9d Chapter 13 of Output Hardcopy Devices (Ed. R. C. Durbeck and S. Sherr, San Diego: Academic Press, 1988) and U.S. Pat. Nos. 4,490,728 and 4,313,684. Inkjet printers produce high quality print, are compact and portable, and print quickly and quietly because only ink strikes a printing medium, such as paper.
An inkjet printer produces a printed image by printing a pattern of individual dots at particular locations of an array defined for the printing medium. The locations are conveniently visualized as being small dots in a rectilinear array. The locations are sometimes xe2x80x9cdot locationsxe2x80x9d, xe2x80x9cdot positionsxe2x80x9d, or pixelsxe2x80x9d. Pixels vary in size, the smaller the dot in the rectilinear array, means that more dots can be printed per inch of the printed medium. Smaller dots result in a more accurate rendition of the image and this in turn results in greater definition of the image. Thus, the printing operation can be viewed as the filling of a pattern of dot locations with dots of ink of specific size or from a combination of different sized dots.
Inkjet printers print dots by ejecting very small drops of ink onto the print medium and typically include a movable carriage that supports one or more print cartridges each having a printhead with a nozzle member having ink ejecting nozzles. The carriage traverses over the surface of the print medium. The width of the carriage varies among the different printers. For any line of print, the carriage may make more than one traverse and utilize a varying number of nozzles. An ink supply, such as an ink reservoir, supplies ink to the nozzles. The nozzles are controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller. The timing of the application of the ink drops is intended to correspond to the pattern of pixels of the image being printed and to the physical properties of the ink and the print media.
In general, the ink is housed in a vaporization chamber with a tube leading to a nozzle exposed to the print media. Small drops of ink are ejected from the nozzles through orifices by rapidly heating a small volume of ink located in the vaporization chambers with small electric heaters, such as small thin film resistors. The small thin film resistors are usually located adjacent the vaporization chambers. Heating the ink causes the ink to vaporize and eject ink in the connecting tubing through the nozzle orifices. Specifically, for one dot of ink, an electrical current from an external power supply is passed through a selected thin film resistor of a selected vaporization chamber. The resistor is then heated and in turn heats a thin layer of ink located within the selected vaporization chamber, causing explosive vaporization, and, consequently, a droplet of ink is ejected from the nozzle and onto a print media. The vacuum created as the ink droplet is ejected from the nozzle acts as a suction pump to draw more ink into the vaporization chamber.
The temperature will be high if the resistors fire a number of times in a short period of time. As the carriage traverses in a print swath, various heater elements in the array are activated. If the traverse is narrow, the mean temperature at the beginning of the traverse will be similar to the mean temperature at the conclusion, and the effect of temperature on the pass will be consistent for all ink droplets projected onto the print media. If the swath is wide more heater elements are activated.
Prior to page wide arrays, ink jet printing was limited in speed due to raster scanning of narrow printheads. This speed has now increased. With page wide arrays, the problem now is to have inks that dry with sufficient speed to allow for multiple passes without compromising the previously printed swaths. This means that either fast drying solvent based inks, which may not be compatible with ink jet material sets, must be used, or use water based ink at very slow speeds to allow for vehicle evaporation.
Therefore, what is needed is a system and method for optimizing ink drying time through the incorporation of a system of multiple spaced printheads. The system and method would divide data into packets to be processed by separate controllers in individual printheads. The printheads would be spaced on carriages along the long axis of the print media so that each printhead prints a portion of the same print swath. As the printed data from the first printhead reaches subsequent printheads, printed data to complete the swath would be added by successive printheads. By the time the printed data from the first printhead reached the second printhead the swath would have had time to dry
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention is embodied in a system and method optimizing ink drying time through the incorporation of a system of multiple spaced printheads.
The printhead assembly includes connection and processing circuitry, multiple printhead bodies, ink channels, substrates, such as semiconductor wafers (commonly referred to as a die), and nozzle members. The nozzle members have heating elements in arrays, as well as plural nozzles coupled to respective ink channels. The printheads also include controllers, which can be integrated circuit processors, printer drivers, firmware or the like for controlling printing on a print media and incorporating a programmable feedback loop. The loop activates the various printheads during printing so that the various data packets are added in a synchronized manner during the print swath.
The controller can be defined in the integrated circuit as receiving the location through an index sensor during the printing process, comparing this index with the set point for printing data packets, initiating various printheads in the printhead assembly, and by a forward communication loop initiate a stepper motor to keep the print media coordinated with the printing process. The controller can be created by any suitable integrated circuit manufacturing or programming process.
The present invention provides adequate drying time for inks produced in a printing swath on a wide array page. This will result in the use of water based inks compatible with ink jet materials in systems with fast raster scanning.